Combined moisture and liquid indicators



July 22, 1958 w. F. WISCHMEYER El'AL 2,844,025

COMBINED MOISTURE AND LIQUID INDICATORS Filed June 18, 1956 2 Sheets-Sheet 1 FIG.I.

20 I INVENTOR, I JOHN E. HOFFMAN WILLIAM F. WISCHMEYER ATTORNEYS.

July 22, 1958 w. F. WISCHMEYER ET AL COMBINED MOISTURE AND LIQUID INDICATORS Filed June 18.- 956 2 Sheets-Sheet 2 FIG.5.V

Unite COMBINED MOISTURE AND LIQUID INDICATORS Application June 18, 1956, Serial No. 592,078

14 Claims. or. 75-73 This invention relates generally to improvements in indicator units for refrigeration systems, and more particularly to combined liquid and moisture indicators.

A sight glass in the liquid line of a refrigeration system has been used for many years to indicate when sufficient refrigerant is in the system in order to obtain optimum cooling conditions. When insufficient refrigerant is present, bubbles of gas will be seen carried along in the liquid underneath the sight glass. Moreover, under abnormal operating conditions there may be a large pressure drop in the liquid line which would cause the refrigerant to expand into a gas even though suflicient refrigerant is present in the system. The sight glass is also useful under these conditions since it will indicate such pressure drop and enable corrective meaures'to be taken to assure operation of the system at full capacity.

Recently, the refrigeration industry has realized that excessive moisture in a refrigeration system has been the cause of many difilculties. One of the major difficulties encountered is a freeze-up of the expansion device in which the moisture forms ice that either blocks the port in the expansion valve or otherwise hinders the action of the valve and restrictor tube. It has also been established that excessive moisture leads to the formation of acids which attack the metal parts of the system. In addition to the actual damage done to the metal parts by the acid, the products of corrosion then circulate and cause further damage.

it is a major objective of the present invention to realize combined liquid and moisture indicators adapted to be installed in the liquid line ahead of the expansion device which will enable by visual determination through a transparent element, the sufiiciency, the pressure conditions and the moisture content of the refrigerant charge so that any undesirable con-'ditionssuch as those discussed above can be quickly corrected.

Another important object is achieved by the advantageous location and arrangement of the moisture-indicating material in the body structure below the transparent element so that the refrigerant and moisture-indicating material can be viewed simultaneously through the transparent element to determine the conditions mentioned previously.

Still another important object is realized by the provision of cup means for holding the moisture-indicating material and by the structural arrangement that places the material in operative communication with the refrigerant in the passage through the indicator body so that the material reacts responsively to the moisture content.

Other important advantages are afforded by the structural arrangement of the cup formation and the means retaining the moisture=indicating material in such formation so that such material, which is usually in a granular form, will not wash away or otherwise contaminate the refrigerant charge.

Yet another important objective is realized by the provision of a plurality of moisture-indicating units in the .body below the transparent element arranged so that each States atent O 2 is visible through such element, as is the refrigerant con-' tained in the liquid line, one unit being adapted to react responsively to one range of percent moisture content while another unit is adapted to react responsively to a different range of percent moisture content, thus enabling a single indicator to be used in systems having different refrigerants.

Another important object is realized by affording liquid and moisture indicators that are simple and durable in construction, economical to manufacture, which can be quickly andeasiy installed in the refrigerant line, and which can be readily used for the purposes discussed with very little instruction.

The foregoing and numerous other objects and advantages of the invention will more clearly appear from the following detailed description of a preferred embodiment and two modifications thereof, particularly when considered in connection with the accompanying drawings, in which:

Fig. l is. a diagrammatic view of a refrigeration system embodying the improved liquid and moisture indicator;

Fig. 2 is a top plan view of the preferred embodiment of a combined liquid and moisture indicator with the closure cap removed;

Fig. 3 is a cross sectional view of the indicator with the cap in place as seen along line 33 of Fig. 2;

Fig. 4 is a fragmentary, top plan view of a modified structure of the liquid and moisture indicator shown with the closure cap removed;

Fig. 5 is a fragmentary, cross sectional view of the modified structure with the closure cap in place as seen along line 55 of Fig. 4;

Fig. 6 is a fragmentary, top plan view of a second modified structure of a combined liquid and moisture indicator shown with the closure cap removed, and

Fig. 7 is a fragmentary, cross sectional view of'the second modified structure with the closure cap in place as seen alongline 7-7 of Fig. 6. t

Referring now by characters of reference to the drawings, and first to Fig. 1, there is shown a diagrammatic view of a refrigeration system including a compressor motor unit generally referred to at 10 that delivers refrigerant to condenser 11. The condenser 11 in turn delivers the refrigerant to a receiver 12, therefrigerant thence being .delivered through a combined liquid and moisture indicator 13 to a thermostatic expansion valve 14, such valve 14 controlling the flow of refrigerant to an evaporator generally indicated at 15. As is usual in a system of this type, the evaporator 15 is connected through suction line 16 back to the inlet side of compressor unit 10. The thermostatic expansion valve 14 includes a sensing bulb 17 located in thermal responsive relation to the outlet of evaporator 15, the bulb 17 causing actuation of valve 14 by reason of thermal effects imparted to bulb 17 in response to changes in superheat in suction line 16.

There are shown and described three different combined liquid and moisture indicator units 13. In each structure, one is able to see the liquid refrigerant and to see the moisture-indicating material disposed within the unit 13 in operative communication with the refrigerant to determine the percent of moisture content.

The moisture indicating salts presently available change color on the basis of the relative saturation of the refrigerant. For example, at F. dichlorodifluoro methane will hold parts per million of moisture in solution in the liquid phase, and monochlorodifluoro methane will hold 1800 parts per million of moisture in a liquid phase. Under these conditions a moisture content of 16.5 parts per million in dichlorodifiuoromethane or parts per million in monochlorodifluoromethane would be equivalent to 10% relative saturation.

The temperature of the liquid refrigerant in the liquid line of a refrigeration system varies depending upon the application. Normal liquid line temperatures are in the range of 75 degrees F. to 125 degrees F, although higher liquid temperatures are not uncommon. Furthermore, the solubility of moisture in dichlorodifluoromethane and monochlorodifiuorornethane varieswith temperature. The significance of this information is that if one attempts to hold a certain absolute value of moisture content in a refrigeration system by means of a moisture indicator which changes color on the basis of relative saturation, then changes in temperature of the refrigerant will cause difliculty.

Both research and experience have indicated that a moisture content of parts per million or below is satisfactory for dichlorodifluoromethane and 60 parts per million or below is satisfactory for monochlorodifluoromethane.

The above table shows how the relative saturation varies with temperature in a refrigeration system operating at the moisture tolerance limit. The relative saturation changes considerably depending upon changes in the temperature of the liquid refrigerant. It is immediately apparent that an indicating unit which changed in the proper range of relative humidity for monochlorodifiuoromethane would not be satisfactory for use with dichlorodifluoromethane. Also, an indicating unit which changed in the range of 5 to 17% relative saturation may not be satisfactory for dichlorodifluoromethane. Since this is such a wide range, two indicating units could be used to give satisfactory indication of the refrigerant moisture content. It is for these reasons that the proposed moisture-indicating devices 13 contain two indicating units, one which changes color in a low range of relative saturation and one which changes color in a higher range. However, it should be pointed out that a single moistureindicating unit may be used in a particular device if it is desired without changing the important constructional features of the ditferent devices subsequently described.

The three different structures of combined liquid and moisture indicators 13 are hereinafter described in detail, corresponding elements being given the same reference numeral where possible for purposes of clarity.

Each of the indicator units 13 includes a body 20 of hexagonal configuration as shown in Fig. 2, the body 20 being provided with an internal chamber 21 (Fig. 3) that is open at the top end. The body 20 is provided with a pair of aligned ports 22 at opposite sides of such body that communicate with the bottom of chamber 21 to provide a passage 23. therethrough. A pair of fittings 24 are united as by brazing, to opposite sides of body 20, each fitting 24 being provided with an internalbore 25 communicating with ports 22 and refrigerant passage 23. The fittings 24 are provided with external threads 26 that facilitate connection of the indicator device in the liquid refrigerant line of the refrigeration system as shown in Fig. 1.

A transparent element 27 such as glass is seated on an internal shoulder 30 formed on body 20 above ports 22, the transparent element 27 closing the top end of chamber 21 and partially defining passage 23. The transparent element 27 constituting a sight glass is attached to body 20 by means of an epoxy type adhesive which .4 gives a strong leak-proof joint that is resistant to heat. With the transparent element 27 located at one side of refrigerant passage 23, the refrigerant in such passage 23 may be viewed directly through transparent element 27 from the open end of body 20.

The body 20 is provided withan integral upstanding collar 31 extending peripherally above transparent element 27, the collar 31 being provided with external and internal threads. Threadedly attached internally of collar 31 is a retaining ring 32 adapted to engage the top peripheral edge of transparent element 27 to assist in retaining element 27 in body 20. This retaining ring 32 atfords an extra safety precaution to prevent conditions. When completely assembled, a gasket 33 is located on top of collar 31 and retaining ring 32, and a closure cap 34 is threadedly attached externally to collar 31, the cap 34 engaging the gasket 33 to provide an effective seal and covering the open end of body 20 to conceal the transparent element 27. This joint can be a metal to metal seal without using the gasket.

In the embodiment shown in Figs. 2 and 3, the transparent element 27 is provided with a pair of spaced cup formations 35 which open at the bottom of element 27 to the refrigerant passage 23. Each cup formation 35 is filled with a moisture-indicating material 36, the material in one cup formation being adapted to react responsive to one range of percent moisture content while the material in the other cup formation is adapted to react responsive to another range of percent moisture content.

The moisture-indicating material 36' is shown as granular and the characteristics are obtained by using various cobalt salts or copper salts. The salts can be impregnated on silica gel, activated alumina, or other solid adsorbent materials, or used by themselves, or deposited on cellulosic material such as unsized paper. Various salt bases and various methods of preparation can be used to get materials which change color at various relative saturations.

The cup formations 35 are enclosed by a porous material that serves to retain the moisture-indicating material 36 in such formations and yet serves to place the material 36 in operative communication with the refrigerant in passage 23. The porous material consists of a subjacent fine mesh screen 38.

A retaining element 40 is located below transparent element 27 and is secured between element 27 and shoulder 30. The retaining element 40 includes a cross piece 41 arranged in bridging relation to cup formations 35 to engage and support the mesh screen 38. Of course, the cross piece 41 is relatively thin compared with the diameter of cup formations 35 so that the moisture-indicating material 36 is in operative communication with the refrigerant at all times In the first modification shown in Figs. 4 and 5, a pair of cup formations 42 are disposed in chamber 21 below transparent element 27, the cup formations 42 being open at the top and at the bottom. The cup formations 42 are preferably constructed of a synthetic material such as nylon. The upper edge of each cup formation 42 is located in contiguous relation to the bottom side of transparent element 27. The resiliency of the synthetic material provides a gasket surface which prevents the refrigerant from washing away the moisture-indicating material 43 with which each cup formation 42 is filled, the moisture-indicating material 43 being visible through the top of the cup formation and through transparent element 27. As suggested previously, the moisture-indicating material 43 of the cup formations 42 may ditfer to cover diflerent ranges of percent moisture content.

The lower ends of cup formations 42 are enclosed by a porous material consisting of a fine mesh screen 45, the porous material being retained by inturned bottom edges on Plp formations 42. Obviously, the moisture-indicat- 5') ing material 43 is in operative communication through the porous material with the refrigerant in passage 23.

Retained between transparent element 27 and shoulder 30 on body 20, is a plate element 46 extending below transparent element 27. The plate element 46 is provided with a pair of apertures adapted to receive the cup formations 42, the plate element 46 engaging the upper edge of each cup formation 42 to retain and press the cupformations 42 against transparent element 27. The plate element 46 is cut away in the region between cup formations 42 and in the regions at each side thereof so that the refrigerant in passage 23 is-clearly visible through transparent element 27.

In the second modified structure shown by Figs. 6 and 7, the body 20 is provided with'a cup formation 50 which opens to the lower side of passage 23, while transparent element 27 is located on the opposite upper side of such passage 23. This cup formation 50 is filled with a moisture-indicating material 51 that is visible through the refrigerant in passage 23 and through transparent element 27.

The moisture-indicating material 51 may be made of activated alumina or some inert material such as aluminum oxide cemented together with a satisfactory bonding agent. After forming, the element is impregnated with a moisture-indicating salt, and is then secured in cup formation 50 by cement or other suitable means. The moisture-indicating element may consist of two parts retained in spaced relation within cup formation 50, each part being impregnated with -a different moisture-indicating salt that is responsive to different ranges of percent relative saturation.

In each of the liquid and moisture indicators represented by Figs. 3, 5 and 7, the refrigerant flowing through passage 23 and hence any bubbles of gas in any such refrigerant, is visible through transparent element 27 when the closure cap 34 is removed. At thesame time, the moisture-indicating material of each structure is visible through transparent element 27. Thus, it is possible to determine visually through the transparent element the sufiiciency, the pressure conditions and the moisture content of the refrigerant charge, all simultaneously.

Although the invention has been described by making detailed reference to a preferred embodiment and two modifications thereof, such detail is to be understood in an instructive, rather than in any restrictive sense, many variants being possible within the scope of the claims hereunto appended.

We claim as our invention:

1. In a liquid and moisture indicator for use in a refrigerant system, a body having an internal chamber open at one end, the body being provided with a passage through said chamber, means on said body for placing said passage in the refrigerant line of the system, a transparent element closing the open end of said chamber adjacent said passage, a .cup formation Within said body enclosed at one end by the transparent element and open at the other end to the refrigerant, and moisture-indicating material located in said cup formation, means enclosing said moisture-indicating material in said cup formation, said means placing said moisture material in operative communication with said passage to permit reaction in response to the amount of moisture contained in the refrigerant, the moisture-indicating material being arranged so that it is visible through said transparent element.

2. In a liquid and moisture indicator for use in a refrigerant system, a body having an internal chamber open at one end, the body being provided with a passage through said chamber, means on said body for placing said passage in the refrigerant line of the system, a transparent element closing the open end of said chamber adjacent said passage, a cup formation within said body enclosed at one end by the transparent element and open at the other end to the refrigerant, moisture-indicating material located in said cup formation, a porous material enclosing and supporting said moisture-indicating material in said cup formation, the moisture-indicating material being placed in operative communication with the refrigerant through said porous material, the moistureindicating material being arranged so that it is visible through said transparent element.

3. In a liquid and moisture indicator for use in a refrigerant system, a body having an internal chamber open at one end, the body being provided with a passage through said chamber, means on said body for placing said passage in the refrigerant line of the system, a transparent element closing theopen end of said chamber adjacent said passage, a pair of cup formations within said body enclosed at one end by the transparent element and open at the other end to the refrigerant, moisture-indicating material located in each said cup formation, the moisture indicating material in one cup formation being adapted to react responsive to one range of percent moisture content while the moisture-indicating material of the other cup formation is adapted to react responsive to another range of percent moisture content, said moisture-indicating material being located in operative communication with the refrigerant in said passage, the moisture-indicating material being arranged so that it is visible through said transparent element.

4. In a liquid and moisture indicator for use in a re-' frigerant system, a body having an internal chamber open at one end, the body being provided with a passage through said chamber, means on said body for placing said passage in the refrigerant line of the system, a transparent element closing the open end of said chamber, a pair of cup formations located Within the body enclosed at one end by the transparent element and open at the other end to the refrigerant, and arranged in relatively spaced relation, a moisture-indicating material located in each cup formation, a porous material enclosing said moisture-indicting material in each cup formation, said moisture-indicating material being placed in operative communication with the refrigerant through said porous material, the moisture-indicating material in one cup formation being adapted to react responsive to one range of percent moisture content while the moisture-indicating material of the other cup formation is adapted to react responsive to another range of percent moisture content, the moisture-indicating material being arranged so that it is visible through said transparent element as is the refrigerant in said passage.

5. In a liquid and moisture indicator for use in a refrigerant system, a body having an internal chamber open at one end, the body being provided With a passage through said chamber, means on said body for placing said passage in the refrigerant line of the system, a transparent element closing the open end of said chamber adjacent said passage, the transparent element being provided with a cup formation, and moisture-indicating material located in said cup formation and arranged in operative communication With the refrigerant in said passage, the moisture-indicating material being arranged so that it is visible through said transparent element.

6. In a liquid and moisture indicator for use in a refrigerant system, a body having an internal chamber open at one end, the body being provided with a passage through said chamber, means on saidbody for placing said passage in the refrigerant line of the system, a transparent element closing the open end of said chamber adjacent said passage, the transparent element being provided with a cup formation, and a moisture-indicating material located in said cup formation, a p'orous'material enclosing said moisture-indicating material in said cup formation, the moisture-indicating material being placed in operative communication with the refrigerant in said passage through said porous material, the moisture-indisaid transparent element being provided with a recessed cup formation that is open at the bottom to said refrigerant passage, moisture-indicating material disposed in said cup formation and visible through said transparent element, a porous material closing the open end of said cup formation and supporting said moisture-indicating material, the moisture-indicating material being placed in operative communication with the refrigerant through said porous material.

8. In a liquid and moisture indicator for use in a refrigerant system, a body having an internal chamber open at one end, the body being provided with a passage through said chamber, means on said body for placing said passage in the refrigerant line of the system, a transparent element closing the open end of said chamber and through which the refrigerant in said passage is visible, said transparent element being provided with a recessed cup formation that opens to the refrigerant passage, moisture-indicating material disposed in said cup formation and visible through said transparent element, a porous material located in the lower end of said cup formation and supporting said moisture-indicating material, and means arranged adjacent the lower side of said transparent element bridging the cup formation and serving to retain said porous material.

9. The combination and arrangement of elements as recited above in claim 8, but further characterized in that the means retaining the porous material consists of a plate element having a perimeter portion and a cross piece, said perimeter portion being retained between said transparent element and said body, the cross piece extending beneath said transparent element in bridging relation to said cup formation, said cross piece engaging said porous material to support said porous material and moisture-indicating material in said cup formation.

10. In a liquid and moisture indicator for use in a refrigerant system, a body having an internal chamber open at one end, the body being provided with a passage through said chamber, means on said body for placing said passage in the refrigerant line of the system, a transparent element carried by said body and closing the open end of said chamber, and through which the refrigerant in the passage is visible, said transparent element being provided with a plurality of recessed cup formations arranged in spaced relation and open at the bottom to the refrigerant passage, moisture-indicating material disposed in each cup formation and visible through said transparent element, a porous material closing the bottom end of each cup formation and supporting the moisture-indicating material in said cup formation, said moisture-indicating material being placed in operative communication with the refrigerant through said porous material, a retaining element secured between said transparent element and said body, the retaining element including a cross piece arranged in bridging relation to said cup formations and engaging said porous material to retain the porous material and moisture-indicating material, the moisture-indicating material in one cup formation being adapted to react responsive to one range of percent moisture content while the moisture-indicating material in another cup formation is adapted to react responsive to another range of percent moisture content.

11. In a liquid and moisture indicator for use in a refrigerant system, a bodyhaving an internal chamber open at one end, the body being provided with a passage through said chamber, means. on said body for placing said passage in the refrigerant line of the system, a transparent element closing the open end of said chamber adjacent said passage, and through which the refrigerant in said passage is visible, a cup formation in the body below said transparent element, said cup formation having an open top end located contiguous to thebottom of said transparent element, moisture-indicating material located within said cup formation and visible through said transparent element, the cup formation having an open lower end, and porous material at the lower end of said cup formation supporting the moisture-indicating material,

said moisture-indicating material being in operative communication with the refrigerant through said porous material.

12. The combination and arrangement of elements as recited above in claim 11, but further characterized by the provision of a retainer element carried by said body and engaging said cup formation to hold said cup formation against said transparent element.

13. The combination and arrangement of elements as recited above in claim 11, but further characterized by the provision of a plate element secured to said body and extending beneath said transparent element, said plate element being provided with an aperture through which the cup formation is received and carried, said plate element engaging said cup formation to hold the open top end against said transparent element.

14. In a liquid and moisture indicator for use in a refrigerant system, a body having an internal chamber open at one end, the body being provided with a passage through said chamber, means on said body for placing said passage in the refrigerant line of the system, a transparent element carried by said body and closing the open end of said chamber adjacent said passage, and through which the refrigerant in said passage is visible, a plurality of cup formations in the chamber below said transparent element and arranged in spaced relation, each of said cup formations having an open top end located contiguous to the bottom of said transparent element, moisture-indicating material located in each of said cup formations and visible through said transparent element, each cup formation having an open lower end, porous material carried by each cup formation enclosing the lower end, the moistureindicating material being arranged in operative communication with the refrigerant in said passage through said porous material, and a plate element secured between said body and said transparent element and extending beneath said transparent element, said plate element being pro vided with a plurality of apertures adapted to receive said cup formations, said plate element engaging said cup formations to urge the open top ends against said transparent element, said plate element being cut away in the region between said cup formations to enable the refrigerant in the passage to be seen through said transparent element.

References Cited in the file of this patent UNITED STATES PATENTS 1,103,985 Murray et a1 July 21, 1914 2,325,657 Burkness Aug. 3, 1943 2,506,806 'Mitzger May 9, 1950 2,534,279 Liberthson Dec. 19, 1950 2,594,113 Askin Apr. 22, 1952 2,613,534 Schreiber Oct. 14, 1952 2,716,338 Blinn Aug. 30, 1955 

